In a related art semiconductor device or the like, a metal, e.g., copper (Cu), is used as a material of a line, but in a micro-line structure formed with a metal line material such as Cu, conduction electrons are intensely affected by inelastic scattering in an interface due to a wire effect, resulting in a problem that a line has a high resistance.
Meanwhile, a nano-carbon material, which is different from the metal, e.g., a graphene has an extremely long mean free path and a high mobility, and when applied to the micro-line structure, the nano-carbon material may also have feasibility of a low resistance line exceeding Cu. Thus, in next-generation semiconductor devices required to realize a finer stacked structure or line structure, the use of the nano-carbon material, instead of Cu, as a material of a line is considered.
The graphene is formed using a catalytic metal layer formed on a surface of a substrate as a base film. Specifically, after a nickel (Ni) film that forms a catalytic metal layer is activated, carbon atoms decomposed from a raw material gas are solved into the activated nickel film, and the carbon atoms are recrystallized to form the graphene. Thus, the quality of the nickel film significantly affects the quality of the graphene.
In order to form a high quality nickel film, for example, a nickel film with a small amount of impurities included therein, it is proposed to use an ammonia (NH3) gas, as well as a hydrogen (H2) gas, as a reduction gas in forming a nickel film by a chemical vapor deposition (CVD) using an organic metal compound which contains a nickel.
However, in addition to the quality of the nickel film, a surface state, in particular, smoothness of the nickel film, also significantly affects the quality of the formed graphene. In this respect, however, in the CVD, a state in which a plurality of small-diameter particles of the nickel are deposited on the nickel film, i.e., a so-called as-deposited state, is maintained to impair the smoothness of the formed nickel film, and thus, the quality of graphene formed by using the corresponding nickel film is not high.